Hydraulic pumping unit



1, 1964 R. L. CHENAULT 3,159,105,

HYDRAULIC PUMPING UNIT Filed Oct. 12, 1962 2 Sheets-Sheet 1 INVENTOR. 32 R0) L. CHE/VAULT WKMV Attorney Unitcd States Patent 3,159,105 HYDRAULIC PUMPING UNIT Roy L. Chenault, Dallas, Tex., assignor to United States Steel Corporation, a corporation of New Jersey Filed 0st. 12, 1962, Ser. No. 230,187 5 Claims; (61. 103-45) 3,159,155 Patented Dec. 1, 1964 and operates the same as the pilot valve shown in FIG- URES l and 2 of my aforementioned earlier patent and its connections with the lifting cylinder and main valve are the same; :in the interest of simplicity I have not repeated the detailed showing nor the description.

I replace the usual sucker rods with a tubular rod string 27 through which fluid pumped from the well is delivered to the surface. The uppermost rod section 27a is fixed to the power piston 12 and extends therethrough and through a stufling box 28 at the top of the lifting cylinder 10. I mount a standpipe 29 on the top of the lower end of the cylinder and relieving the lower end.

The power piston is attached to a polished rod, which in turn is attached to a sucker rod string extending to a subsurface pump at the bottom of a well. Such units offer an advantage of providing a much longer stroke than a mechanical unit, but they usually require an elaborate counterbalance mechanism to equalize the load on the motivating pump during upstrokes and downstrokes. As the parts descend during a downstroke, the motivating pump delivers fluid to a counterbalance tank, where it builds up pressure. The energy thus stored assists the pump in lifting the parts during the next upstroke. Reference can be made to my earlier Patent No. 2,665,551 for a showing of several embodiments of pumping units of this type.

An object of the present invention is to provide an improved combination of hydraulic pumping unit and subsurface pump which operates with acceptable efliciency without dependence on a counterbalance mechanism, thereby simplifying the structure.

A further object is to provide a combination of the foregoing type in which the subsurface pump delivers well fluid to the surface only during its downstroke and takes in well fluid during its upstroke, thereby diminishing the difference in load during the two strokes.

In the drawing:

FIGURE 1 is a diagrammatic vertical section of my improved hydraulic pumping unit;

FIGURE 2 is a diagrammatic vertical section of a subsurface pump I use in combination with my pumping unit; and

FIGURE 3 is a diagrammatic vertical section of a modified pumping unit constructed in accordance with my invention, omitting some parts which are the same as in FIGURE 1.

FIGURE 1 shows a pumping unit which comprises a lifting cylinder 10, a power piston 12 reciprocable up and down in said cylinder, a motivating pump 13, a main valve 14 and a pilot valve 15. Pump 13 draws hydraulic fluid from a reservoir 16 and discharges it through a pipe 17 which has branches 17a and 17b leading to the lower end of the lifting cylinder 10 audio the main valve-14 respectively. Branch 17a contains a flow control valve 18. A pipe 19 connects the main valve with the reservoir 16, and a scavenger pipe 20 connects the upper end of the lifting cylinder 10 with the reservoir. The main valve has an operating mechanism which includes a hydraulic cylinder 21 and a reciprocable piston 22 mounted in said cylinder. A spring 23 urges the piston to a position in which the main valve is open, that is, in which the valve allows fluid from pump 13 and branch 17b to flow into pipe 19. A pipe 24 connects cylinder 21 with the pilot valve 15. When the pilot valve moves to a position in which it admits hydraulic fluid to pipe 24, the resulting pressure on piston 22 closes the main valve against the action of spring 23. The pilot valve 15 is constructed lifting cylinder above this stuffing box. Fluid pumped from the well discharges from the rod string into this standpipe, which has an outlet pipe 30. The rod string extends down the well through a conventional tubing string 31 and casing 32. The upper ends of the tubing and casing have gasvents 33 and 34.

FIGURE 2 shows a subsurface pump which comprises a stationary barrel 35, a standing valve 35 at the bottom of the barrel, a reciprocable hollow plunger 37 fitted in said barrel, and a traveling valve 38 in said plunger. An adapted 39 connects the barrel to the bottom of the tubing string 31. The adapter has vent ports 40 to permit application of easing pressure to the plunger at all times. The lowermost rod section 27b has an enlargement 41 spaced from its bottom end, a series of prongs 42 extending downwardly from said enlargement, and additional enlargements 43 at the bottoms of said prongs. The upper end of plunger 37 is shaped to receive these prongs, which snap into place when the rod string is lowered into the tubing 31 or pull free when the rod string is raised after the plunger reaches the top of the barrel. The enlargement 41 has an external groove which contains an 0 ring 44 to afford a seal between the rod string and plunger. Preferably the lowermost rod section contains a check valve 45 to prevent the weight of the fluid inside the rod string from being supported on the plunger proper.

In operation, the motivating pump 13 delivers hydraulic fluid continuously from the reservoir 16 through pipe 17. When the main valve 14 is closed, fluid passes from the pump through branch 1711 into the lower portion of the lifting cylinder 10. The power piston 12, rod string 27, and the subsurface pump plunger 37 make their upstroke, during which the standing valve 36 opens and the traveling and check valves 38 and 45 close. The plunger draws well fluid into the pump barrel 35, but no fluid is delivered to the surface. Thus the load during an upstroke is restricted substantially to the weight of the rod string. When piston 12 reaches the top of the lifting cylinder, the pilot valve 15 shifts to relieve the valve operating cylinder 21, whereupon the main valve opens (the position FIGURE 1 shows). Fluid from both the motivating pump 13 and the lower portion of the lifting cylinder flow through the main valve into pipe 19 and return to the reservoir 16. Piston 12, rod string 27 and the subsurface pump plunger 37 make their downstroke gravitationally, duringv which the traveling and check valves 38 and 45 open and the standing valve 36 closes. Descent of the plunger forces Well fluid from the pump barrel 35 up the tubular rod string 27 to the surface. The purpose of the flow control valve 18 is to limit the rate of fall of the power piston and rod string. The rate can become 'I have not repeated the showing of the'litting cylinder nor the pilot valve. The modified unit comprises a counterbalance tank 48 anda somewhat more elaborate mam 'valve 49. The main valve includes a housing 50, a slide member '51 within saidhousing, and'a spring 52 which urges the slide member upwardly. The housing has-ports to which are connected a pipe 53 leading from the discharge side of the motivating pump 13, a pipe 54 leading to the'reservoir 16, and a pipe 55 leadingto'the lower end of the lifting cylinder. The ends of the housing have controlports to-which are connected a pipe "56 which leads to-the'pilot valve and a pipe 57 which leads to the reservoir 16. A pipe'58 is connected to;pipe-5-3'and has branches 58a and-58b which lead to the counterbalance tank 48. Branchfitia contains a'fiow control valve-59, and branch 58b a check valve 60 which allows flow through the branch into the tank but prevents reverse flow. In operation, the motivating pump 13 delivers hydraulic fluid continuously from the reservoir, as in the -embodiment already described. When theslide member 51 of the main valve 49-i-s in the-position illustrated, there is communication between-pipes 54 an'd'55 to relieve the lowerend ofthe lifting cylinder and the parts make a downstroke gravitationally. The output of the motivating pump 13 passes'through pipe 58 and branch 58b to the counterbalance tank 43'Wh616 it builds up pressure. When the powerpiston reaches-the bottom of the lifting cylinder, the pilot valve shiftstoapply'pressure to the main valve'housing 50 through pipe 56. The slide-member Sishifts to establish communication between pipes 53 and 55. Both the motivatingpump-13 and the counterbalance tank 48 deliver fluid to the lower end of the lifting cylinder to'produce an upstroke. Since fluid is raised to the surface under gravitational descent of the rod string, this embodiment equalizes the load during the two strokes with a simple counterbalance and a smaller motivating pump than used in the first embodiment.

From the'foregoing description it is seen thatmy invention affords a relatively simple pump combination which diminishes the dilference in loadduring-the two strokes without a counterbalance, or'equalizes the load -with an extremely simple counterbalance. The combination alsoolfers several other advantages. I can use a subsurface pump as'large as I can run into a well casing and still utilize a gas separator below'the pump and permit gas to vent through the casing. Any, paraifin 'deposits are confined'to the tubular rod string where I can remove themwith wire line scrapers without the necessity for pulling sucker rods.

While I have shown and described certain'pre ferred embodiments of my invention, it is apparent that other modifications may arise. Therefore, I, do not wish to be limited to the disclosure set'forth but only by the scope of the appended claims.

I claim:

1. In .a pumping installation which includes in. combination a hydraulically operatedsurface pumping unit,

i a subsurface purnp below said unit, and means operatively connecting said pumping unit and said subsurface pump, said pumping unit comprising a lifting cylinder, a power piston reciprocable up and down in said cylinder, at motivating pump, and valve means for alternately directing fluid from-said motivating pump to the lower end of said cylinder'to lift said piston during an upstroke and relieving the lower end of said cylinder to allow said piston to descend gravitationallyduring a downstroke, said pump comprising a barrel, a standing valve at the lower end of said barrel, a reciprocable plunger mounted in said barrel, and a traveling valve carried by said plunger,-said standing valve openingand' said traveling valve closing as said plunger makes an upstroke to enable the plunger to draw Yfluid intothe barrel, said standing valve closing and'said -traveling'valve opening as saidplunger makes'a downstroke-to enable the plungerto displace fluidfrom the -barr'el,-said connecting means comprising a tubular'rod string-attached to'said piston and to'said plunger for moving the plunger with thepiston and delivering to the surface during a downstroke fluid displaced from said barrel, the weight ofsaidrod: string furnishing theforce which lifts thefluid to the surface, whereby the load during an upstroke is restricted substantially to the weight of the rod string.

ZVApumping installation as defined'in claim 1 in which said pumping-unit lacks acounterbalance mechanism and relies onthe use of gravitational force delivering-fluid to the surface as a meansfor diminishing the difference I in 'load duringupstrokes and downstrokes.

3. A pumping. installation as defined in claim 1 in which said pumping unit comprises a counterbalance tank intowhich said motivating pump delivers/fluid during a downstroke, and from which fluid is delivered to said lift- :ing'cylinder during an upstroke, said counterbalance tank 1 equalizing the load during the two strokes.

'4. A pumping installation as defined in claim 1 in which said pumping unit. comprises 'a standpipe mounted on the top of said lifting cylinder, and-said rod string extends through said: pisto-nand delivers" fiuid' into said standpipe.

-5. Apumping installation :as defined inclaim 1 in which" the lower end portion of said rod string includes a series of: prongs and said plunger is shaped to receive said prongs to fix the plungerlto the rod string, said'prongs snapping into engagement with said plunger as said rod string-is lowered 'andpulling free as saidrod string is raised when the plungerreaches the top of the barrel.

References Gited in the file'of this patent I UNITED STATES PATENTS 245,101 Thayeret al. ..'.Aug. 2, 1881 565,548 Lippy Aug. 11, 1896 1,765,457 Shutt ..-June24, 1930 1,777,981 7 Mason Oct. 7,1930 2,180,158 McCoy et al Nov. 14, 1939 2,560,441 ,Holl July 10, 1951 2,665,551 Chenault 'Jan. 12, 1954 3,064,580 -Calvert etal u Nov. 20, 1962 

1. IN A PUMPING INSTALLATION WHICH INCLUDES IN COMBINATION A HYDRAULICALLY OPERATED SURFACE PUMPING UNIT, A SUBSURFACE PUMP BELOW SAID UNIT, AND MEANS OPERATIVELY CONNECTING SAID PUMPING UNIT AND SAID SUBSURFACE PUMP, SAID PUMPING UNIT COMPRISING A LIFTING CYLINDER, A POWER PISTON RECIPROCABLE UP AND DOWN IN SAID CYLINDER, A MOTIVATING PUMP, AND VALVE MEANS FOR ALTERNATELY DIRECTING FLUID FROM SAID MOTIVATING PUMP TO THE LOWER END OF SAID CYLINDER TO LIFT SAID PISTON DURING AN UPSTROKE AND RELIEVING THE LOWER END OF SAID CYLINDER TO ALLOW SAID PISTON TO DESCEND GRAVITATIONALLY DURING A DOWNSTROKE, SAID PUMP COMPRISING A BARREL, A STANDING VALVE AT THE LOWER END OF SAID BARREL, A RECIPROCABLE PLUNGER MOUNTED IN SAID BARREL, AND A TRAVELING VALVE CARRIED BY SAID PLUNGER, SAID STANDING VALVE OPENING AND SAID STANDING VALVE CLOSING AS SAID PLUNGER MAKES AN UPSTROKE TO ENABLE THE PLUNGER TO DRAW FLUID INTO THE BARREL, SAID STANDING VALVE CLOSING AND SAID TRAVELING VALVE OPENING AS SAID PLUNGER MAKES A DOWNSTROKE TO ENABLE THE PLUNGER TO DISPLACE FLUID FROM THE BARREL, SAID CONNECTING MEANS COMPRISING A TUBULAR ROD STRING ATTACHED TO SAID PISTON AND TO SAID PLUNGER FOR MOVING THE PLUNGER WITH THE PISTON AND DELIVERING TO THE SURFACE DURING A DOWNSTROKE FLUID DISPLACED FROM SAID BARREL, THE WEIGHT OF SAID ROD STRING FURNISHING THE FORCE WHICH LIFTS THE FLUID TO THE SURFACE, WHEREBY THE LOAD DURING AN UPSTROKE IS RESTRICTED SUBSTANTIALLY TO THE WEIGHT OF THE ROD STRING. 